essay sources of water on earth

Essay on Sources of Water

Students are often asked to write an essay on Sources of Water in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on Sources of Water

Introduction.

Water is a vital resource for all life forms. It is obtained from various sources like rivers, lakes, groundwater, and rain.

Rivers and Lakes

Rivers and lakes are significant sources of fresh water. They are replenished by rain and melting snow.

Groundwater

Groundwater is water found underground in soil or rocks. Wells and boreholes are used to extract it.

Rainwater is another essential source. It replenishes rivers and lakes and can be collected directly in rainwater tanks.

Understanding these sources is crucial for conserving and managing our water resources wisely.

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250 Words Essay on Sources of Water

Water is the lifeblood of our planet, vital for all forms of life. It is a universal solvent, making it a critical resource for various industries. However, the sources from which we obtain this indispensable substance are diverse and complex.

Natural Water Sources

Natural sources of water, also known as surface water, primarily include rivers, lakes, and ponds. These bodies of water are replenished through precipitation and run-off from surrounding land. Groundwater, another natural source, is stored in aquifers beneath the Earth’s surface, replenished through the process of infiltration.

Artificial Water Sources

Artificial sources of water, on the other hand, are man-made and include reservoirs, wells, and canals. Reservoirs are typically created by damming rivers, storing large volumes of water for various uses. Wells tap into underground water sources, while canals are designed to transport water from one location to another.

Ice Caps and Glaciers

Ice caps and glaciers, although not readily accessible, represent a significant source of fresh water. They store about 69% of the world’s fresh water, which can be unlocked through melting, although this is heavily influenced by climate change.

Understanding the various sources of water is crucial for sustainable management and conservation. While natural sources are replenished through the Earth’s hydrological cycle, human intervention is often required to tap into these sources effectively. As the demand for water increases, innovative methods to harness and conserve this vital resource are becoming increasingly necessary.

500 Words Essay on Sources of Water

Water, the lifeblood of our planet, is a fundamental requirement for the survival of all known forms of life. It is a finite resource, and its availability is under increasing pressure due to growing populations and environmental changes. Understanding the sources of water is crucial for effective management and conservation of this vital resource.

Surface Water

Surface water is the most visible and directly accessible source of water. It includes bodies of water like rivers, lakes, and ponds, which are replenished by precipitation and run-off from surrounding land. Rivers, for instance, are a major source of fresh water for many communities. They are replenished by rainfall and snowmelt and are also fed by underground sources. Lakes, both natural and man-made, store vast quantities of water and serve as essential sources for drinking, irrigation, and hydroelectric power.

Groundwater is another significant source of fresh water. It is found in aquifers, which are underground layers of rock, sand, or gravel that hold water. This water is accessed through wells and boreholes. Groundwater is a critical resource, particularly in regions where surface water is scarce or seasonal. It is replenished by the infiltration of rainwater through the soil, a process known as recharge. However, the rate of recharge is often much slower than the rate of extraction, leading to concerns about sustainability.

Rainwater is a primary source of all water on Earth. It replenishes both surface water and groundwater. Rainwater harvesting, the practice of collecting and storing rainwater for future use, is an increasingly important strategy for water management, particularly in arid regions and urban areas. It can provide a sustainable, decentralized source of water that reduces reliance on other, often over-stressed, water sources.

Desalination

With over 70% of the Earth’s surface covered by saltwater, desalination, the process of removing salt and other minerals from seawater, provides a potential source of fresh water. While historically expensive and energy-intensive, technological advances are making desalination a more viable option, particularly in water-scarce coastal regions.

Ice and Snow

In colder climates, ice and snow serve as significant water sources. Glaciers and snowpack act as natural reservoirs, storing water in the winter and releasing it in the spring and summer as they melt. This source is particularly important for regions that rely on meltwater for their water supply. However, climate change threatens the reliability of these sources.

In conclusion, our water comes from a variety of sources, each with its own characteristics and challenges. Understanding these sources and their dynamics is crucial for ensuring the sustainable management of our water resources. As pressures on water availability increase, strategies such as rainwater harvesting and desalination will become increasingly important. However, the conservation of water should remain a priority, as the preservation of our water sources is critical for the survival of life on Earth.

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Science News

How did earth get its water.

The answer lies in deuterium ratios and a theory called the Grand Tack

WATER, WATER EVERYWHERE   Earth is a wet planet that formed in a dry part of the solar system. How our planet’s water arrived may be a story of big, bullying planets and ice-filled asteroids. 

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By Christopher Crockett

May 6, 2015 at 11:14 am

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Earth — a planet of oceans, rivers and rainforests — grew up in an interplanetary desert.

When the solar system formed about 4.6 billion years ago, shards of calcium- and aluminum-rich minerals stuck together, building ever-larger pebbles and boulders that smashed together and assembled the rocky planets, including Earth.

But Earth’s signature ingredient was nowhere to be found. Heat from the young sun vaporized any ice that dared to come near the inner planets. Earth’s relatively feeble gravity couldn’t grab on to the water vapor, or any other gas for that matter. And yet, today, Earth is a planet that runs on H 2 O. Water regulates the climate, shapes and reshapes the landscape and is essential to life. At birth, humans are about 78 percent water — basically a sack of the wet stuff.

To get water, Earth had to have help from somewhere else.

Researchers recently found traces of Earth’s aquatic starter kit locked away inside several meteorites, chunks of rock that fell to the planet’s surface. Those meteorites were a gift from Vesta, the second largest body in the asteroid belt between Mars and Jupiter. Vesta is thought to have formed earlier than Earth, roughly 8 million to 20 million years after the start of the solar system. (Earth needed 30 million to 100 million years to pull itself together.)

Well before the rocky planets formed, recent research suggests, ice-infused asteroids were forged beyond Jupiter and subsequently swarmed the inner solar system. These space rocks delivered water to Vesta and to Earth after being hurled at our planet by the gravity of Jupiter and Saturn. Whether the giant planets were a help or a hindrance is anybody’s guess. But if what happened here can happen anywhere, then water might be prevalent on other worlds, giving life a good chance of thriving throughout the galaxy.

Comets vs. asteroids

For decades, researchers have debated whether comets or asteroids delivered Earth’s water. At first glance, comets seemed a likely source. Originating beyond the orbit of Neptune, comets are the deep-freeze storage units of the solar system. They hold a lot of ice that has been locked away within their interiors since the formation of the solar system. Some comets are occasionally thrown inward after a close brush with a planet or passing star. It makes sense that, during the chaos of the early solar system, Earth would have been pummeled with comets, bringing plenty of water to fill the oceans.

In recent years, however, the comet hypothesis has lost favor. “It looks like comets are pretty much out,” says cosmochemist Conel Alexander of the Carnegie Institution for Science in Washington, D.C. Most of the comet water tested so far doesn’t match that of Earth’s oceans. Plus, it’s incredibly difficult to bring a comet toward Earth, much less a whole slew of them. “It just shouldn’t be part of the discussion anymore,” he says.

Part of the problem lies in a subtle chemical difference between water on Earth and water in most comets. Water is a simple molecule resembling a pair of Mickey Mouse ears: two hydrogen atoms grab a single oxygen atom. But sometimes deuterium, a slightly heavier version of hydrogen, weasels its way into the mix. The nucleus of a deuterium atom contains one proton and one neutron; in hydrogen, the proton stands alone. On Earth, only about 156 out of every 1 million water molecules contain deuterium.

Most comets appear to follow that logic; their D/H ratio is typically about twice what has been measured on Earth.

Two comets, however, threw a curveball at scientists who had counted out comets as the source of Earth’s water. In 2010, researchers used the Herschel space telescope to measure the D/H ratio of comet 103P/Hartley 2. They reported that 103P’s water nearly matched that found on Earth. Observations of comet 45P/Honda-Mrkos-Pajdušáková three years later also found abnormally low D/H ratios. Suddenly one, possibly two, comets were carrying Earthlike water.

Jupiter’s pull

Both of these comets are part of a community known as Jupiter family comets. They originated in the Kuiper belt, the ring of icy debris beyond Neptune where Pluto lives. The gravity of first Neptune and then Jupiter gradually nudged these comets into relatively short orbits that bring them closer to the sun. All previous D/H measurements were of comets that hail from the far more distant Oort cloud, a shell of ice fragments that envelops the solar system. Comets 103P and 45P suggested that researchers may have been hasty in dismissing all comets as Earth’s water source. Perhaps just the Jupiter family comets were responsible.

But then in 2014, the European Space Agency’s Rosetta probe arrived at Comet 67P/Churyumov–Gerasimenko, another Jupiter family comet. As the spacecraft sidled up to the comet, it sampled the water streaming from the comet body and found 67P’s D/H ratio to be staggeringly high — more than three times that of Earth’s oceans ( SN: 1/10/15, p. 8 ).

“Each new comet measurement is giving us a different picture,” says Karen Meech, a planetary scientist at the University of Hawaii in Honolulu. The Rosetta results show that even among a single family of comets, there is incredible diversity in water composition. “Comets formed over a huge range of distances, so it’s no surprise that there’s a huge range in D/H,” she says.

But even if some comets have an Earth-like D/H ratio, it’s still really hard to get comets to hit our planet in the first place. “Any comet that’s going to bash into Earth has to get past this really big linebacker of Jupiter,” says planetary scientist Sean Raymond of the Laboratoire d’Astrophysique de Bordeaux in France. Jupiter has a tendency to take comets that come too close and fling them out of the solar system. The few that do end up on Earth-crossing orbits don’t stay there for long.

“The comet only has a certain number of tries to get in close and either hit Earth or get scattered on to another orbit,” Raymond says.

So Jupiter’s gravity may be too big a hurdle for comets to overcome. But it may be just the ticket for flinging asteroids at the inner planets.

A more ‘tack’-ful approach

In 2011, a team of researchers including Raymond were tackling a different problem: Why is Mars so small? There should have been plenty of raw material available 4.6 billion years ago to turn Mars into a planet closer in size to Venus or Earth. But Mars is just about half Earth’s diameter and about one-tenth its mass. One possible explanation is that something prematurely robbed the nascent Red Planet of its building blocks.

One solution, known as the Grand Tack model, describes a solar system far less sedate than the one we inhabit today ( SN Online: 3/23/15 ). In the Grand Tack scenario, Jupiter and Saturn stride back and forth across the solar system like schoolyard bullies, hurling rocks at and stealing food from the other planets. The gas that encircled the sun dragged Jupiter and then Saturn inward. Once Jupiter arrived at about the current orbit of Mars, a gravitational tug from Saturn flung both back out from where they came (the “tack” in “Grand Tack”).  Jupiter’s encroachment on the inner solar system carved a gap in the debris field from which the rocky planets were forming, depriving Mars of raw ingredients.

Story continues below slideshow

WATER HERE AND THERE 

Along with Earth, a couple of dwarf planets and several moons have shown evidence of water, in one form or another. Their potential to support life varies. 

The same planetary tango that robbed Mars of resources might also explain how icy asteroids pummeled Earth. As Jupiter and Saturn wandered back out, their gravity latched on to asteroids that formed beyond the snow line — the boundary beyond which temperatures are low enough for ice to form — and flung them inward. About 1 percent of these ice-infused boulders, known as C-type asteroids, were dropped into the outer regions of the asteroid belt. But for every C-type asteroid relocated to the belt, at least 10 were sent careening into the region where the rocky planets were materializing.

This bombardment of asteroids a few million years after the start of the solar system could have easily delivered enough ice — locked inside the rocks, safe from the sun’s heat — to account for Earth’s oceans, computer simulations indicate. Water makes up to about 20 percent of the mass of some of these asteroids. On Earth, despite having more than 70 percent of its surface blanketed in blue, water accounts for only 0.023 percent of the planet’s mass. Compared with some asteroids, Earth is positively parched.

The Grand Tack nicely explains the formation of Mars, the layout of the asteroid belt and the delivery of water to Earth via icy asteroids. But Raymond stresses that it’s just one way to match all the data. “It’s an evolution of thinking,” he says. “It’s not meant to be a final solution.”

The same D/H ratio that exonerated comets is now pointing a finger at these asteroids. In 2012, Alexander and colleagues concluded in the journal  Science  that the bulk of Earth’s water arrived via bodies similar to a class of meteorites known as CI carbonaceous chondrites. Researchers think that these meteorites, which were knocked off asteroids that formed beyond Jupiter, are among the oldest objects in the solar system.

Alexander’s research, along with that of many others, builds a strong case for a chemical match between Earth’s water and chondrites’ water. But it doesn’t address when the water arrived. Brown University geologist Alberto Saal argues that part of the answer lies on the moon.

Story continues below graphic

The bounty of lunar samples brought to Earth by Apollo astronauts included volcanic glass hauled in during the Apollo 15 and 17 missions. The glass formed from rapidly cooling magma that was spat out from the moon’s interior long ago. In 2013, Saal and colleagues reported in  Science  that the D/H ratio of water trapped within the glass matched that measured in both Earth’s oceans and Alexander’s carbonaceous chondrites ( SN: 6/29/13, p. 8 ). Saal’s findings suggest two things: Earth and the moon have a common source of water and the water was already here when the moon formed.

The moon started with a literal bang. A planet the size of Mars is thought to have smashed into Earth toward the end of our planet’s formation. The collision blasted part of Earth, as well as the unfortunate interloper, into a ring of vaporized rock that encircled Earth before sticking together to build the moon ( SN: 7/12/14, p. 14 ). Water must have been present at the time of impact for it to be sealed into the moon, Saal notes, or it at least arrived before the moon’s surface had time to cool and solidify. This puts water near Earth about 150 million years after the start of the solar system. But based on the moon data alone, we can’t say how much earlier, says Sune Nielsen, a geologist at the Woods Hole Oceanographic Institution in Massachusetts.

To narrow in on a more precise time for water’s arrival, researchers have turned to the asteroid Vesta. Or, more specifically, meteorites nicked off Vesta after the asteroid got whacked by another space rock. Woods Hole geologist Adam Sarafian, Nielsen and colleagues analyzed small amounts of water trapped within minerals of apatite locked inside a sample of Vesta meteorites. The team reported last fall in Science that the D/H ratio of the meteorites’ water matched Earth’s. That discovery implies that whatever delivered Vesta’s water brought along Earth’s as well and that this water had to have arrived before Vesta finished forming ( SN Online: 11/1/14 ).

That finding pushes the influx of water back, possibly as early as 8 million years after the start of the solar system. This is the oldest stockpile of water ever dated in the solar system, Nielsen says. These observations place water in the inner solar system well after Jupiter and Saturn were on the prowl, lobbing asteroids around the solar system.

Nailing down how and when water arrived at Earth is about more than just understanding how our planet was built. “If you have to have some sort of external delivery mechanism for getting water to terrestrial planets,” says Alexander, “it becomes harder to make a habitable planet.” Rocky planets forming around other stars will face the same problem that Earth faced. These planets in the habitable zones of their stars, while able to support liquid water on their surfaces, develop in dry environments and need to have ice sent in from farther out. Did Earth get lucky by having Jupiter and Saturn as neighbors, or are there other ways to move water around?

Just because Earth formed one way doesn’t mean all habitable planets must follow the same path. “I would be cautious,” Nielsen says, about saying that gas giants are the only way to bring water to rocky planets.

In fact, gas giants may even be a hindrance. “Jupiter and Saturn just screw things up,” says Raymond. Their gravity is strong enough that they tend to kick asteroids and comets right out of the solar system. If Jupiter and Saturn didn’t exist, he notes, Earth’s gravity could have stolen 10 times as much water from the outer edge of the asteroid belt. In the absence of giant planets, water delivery could happen naturally as planets pull in debris from different parts of the solar system. Recent observations from the Kepler space telescope suggest that planets the size of Jupiter are relatively uncommon around other stars. Perhaps most habitable planets do just fine on their own.

If that’s the case, then maybe the galaxy is teeming with ocean worlds waiting to be discovered. “From my point of view,” Raymond says, “having water on a planet like Earth is an everyday occurrence.” 

WET AND WILD   Earth may have Jupiter and Saturn to thank for sending it water way back when. The two gas giant planets did a gravitational dance with the sun and each other that sent them hurling in then back out to the outer solar system. In reaction, a bunch of icy asteroids shot into the inner solar system, pummeling early Earth and bringing it water, as shown in this animation.  Credit: Drawings by Helen Thompson; Images courtesy of NASA; Narrated and produced by Helen Thompson and Ashley Yeager

This article appears in the May 16, 2015, issue with the headline, “Water, water everywhere: Every bit of Earth’s H 2 O was delivered by space rocks, but which ones?”

Editor’s note: This story was corrected on May 18, 2015. A caption incorrectly referred to hydrogen molecules, instead of hydrogen atoms.  The  Water Here and There  slideshow was corrected and updated on May 20.

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Why is water important?

We're often told that we need to drink more water, but exactly why is water important?

Why do we need to drink water?

What happens if you don’t drink enough water, what effect does water have on the body, drinking enough water.

If you’ve been pondering the question ‘why is water important?’ rest assured, you’re not alone. While it probably won’t come as a surprise to hear that everyone needs to drink water to survive, most of us invest in one of the best water bottles and commit to guzzling down our daily water intake without really understanding what makes water so vital.

There are quite a few things that make water necessary to the human body, from cellular functions, to aiding digestion, and even improving concentration and exercise performance. You’ve probably even heard the recommendation to drink a certain amount of water every day (usually about 8 glasses or so), but where does that number come from? And what happens if you don’t drink enough?

This article will tackle everything and anything you would need to know about why water is important, including why we need to drink water, what happens when we don’t get enough and the effect water has on our body. Let’s dive in!

Knowing how to stay hydrated with water is super important. Why? Well, largely because the human body is about 60% water and because we are continuously losing water through urine, sweat and even just breathing, we need to ensure we’re replacing that fluid so that our cells, tissues and organs can all function optimally.

Water is a solvent, which means that other substances can dissolve in it, which allows for their transportation between cells in the body. Substances like glucose (the body’s preferred fuel source) and amino acids (the building blocks of protein) dissolve very effectively in water, and use water as a carrier for them throughout the body. 

Water also carries vitamins and minerals to and from the cells, and is vital in removing waste products from individual cells, as shown by research in the Biochemical Journal . Further, water consumption ensures appropriate blood volume, viscosity, and circulation, which is vital for the proper function of all organs and tissues of the body, according to a paper in Nutrition Reviews .

Water is also vitally important for regulating body temperature. It has a great capacity to store heat, preventing large, rapid drops in internal temperature, and through sweating, water has arguably the most efficient avenue to lose heat when environmental temperature is higher than body temperature, as per an article in Military Medicine .

Finally, water is essential to form many bodily fluids: tears, saliva, sweat, urine, and blood, amongst others. Water is also a highly effective lubricant for joints helping to produce synovial fluid and cartilage, which help keep joints healthy through smooth movements. Water also helps with joint health by maintaining cells’ shapes, acting as a shock absorber during impacting activities like walking or running, which even protects the brain and spinal cord, according to a review article in Nature . 

Not drinking enough water can lead to dehydration very quickly, and it’s more common than we think. According to a 2020 paper in StatPearls , between 28% and 75% of adults in the US are dehydrated at any given moment. This is

attributed to a number of factors, notably overconsumption of caffeinated drinks like coffee and soft drinks, which a 2018 study in Nutrients lists as common replacements for water that act as a diuretic that cause the body to lose even more water. 

Even ‘mild’ dehydration (a loss of water corresponding to 1-2% of body weight) can lead to significant impairments in cognitive function, concentration, alertness, memory, physical performance, sport-specific skills, and physical endurance, according to research in Nutrition Reviews .

According to a study in the Journal of Applied Physiology , larger losses in water corresponding to 4% of body weight (which research still considers ‘mild’) can lead to poor cardiovascular function as blood plasma volume drops which causes an increase in heart rate and stroke volume (the amount of blood the heart perfuses per beat). Dehydration of this level can also cause decreases in skin blood flow and sweating, which leads to an increase in body temperature, which can complicate any heat-induced dehydration, as per another study from the Journal of Applied Physiology . 

As you may be able to tell, drinking water will have more or less the opposite effect to not drinking water, for all the reasons outlined earlier in the article. In an ideal world, we would all stay hydrated by drinking water regularly, and so we may never notice the effect that drinking water has because we’d never be dehydrated. However, we know that not to be the case. 

Given the host of cognitive problems that dehydration can have on the body, drinking water can often improve your ability to focus, concentrate, and retain information. A lot of people also ask the question ‘does drinking water help you to lose weight?’ and evidence suggests that it absolutely can. Not only that, it aids in digestion, due to its role in nutrient absorption, and creation of digestive fluids and enzymes like hydrochloric acid. Drinking water can also reduce joint pain or wear and tear, due to its role in joint cushioning and maintenance of synovial fluid and cartilage.

Clearly, drinking water is utterly vital for a whole host of reasons, and unfortunately, just drinking water when thirsty isn’t going to be enough. Thirst is only triggered when water losses correspond to 1-3% body weight, which is enough to lead to mental and physical impairments. Plus, the issue with only drinking when thirsty is that thirst can be quenched before proper hydration is achieved, according to Nature . 

The U.S. National Academies of Sciences, Engineering, and Medicine recommend drinking 92 fluid ounces (11.5 cups) per day for women, and 124 fluid ounces (15.5 cups) of water per day for men. However, many factors can affect how much water someone needs to drink: warmer environments increase sweating and water loss, drinking caffeinated drinks leads to a diuretic affect, and when exercising, sweat and respiration-induced water losses can reach 65 fluid ounces per hour according to a paper in the Journal of the American College of Nutrition .

It’s important to adjust your water intake appropriately to get all of its benefits, and avoid the potential downfalls of dehydration. If you’re keen to find new and novel ways to increase your water intake, check out our guide to how to drink more water.

HÄUSSINGER, D. (1996). The role of cellular hydration in the regulation of cell function. Biochemical Journal, 313(3), 697–710. https://pubmed.ncbi.nlm.nih.gov/8611144/

Jéquier, E., & Constant, F. (2009). Water as an essential nutrient: the physiological basis of hydration. European Journal of Clinical Nutrition, 64(2), 115–123. https://www.nature.com/articles/ejcn2009111

José, G. A., Mora-Rodríguez, R., Below, P. R., & Coyle, E. F. (1997). Dehydration markedly impairs cardiovascular function in hyperthermic endurance athletes during exercise. Journal of Applied Physiology, 82(4), 1229–1236. https://pubmed.ncbi.nlm.nih.gov/9104860/

Montain, S. J., Latzka, W. A., & Sawka, M. N. (1999). Fluid Replacement Recommendations for Training in Hot Weather. Military Medicine, 164(7), 502–508. https://pubmed.ncbi.nlm.nih.gov/10414066/

Murray, B. (2007). Hydration and Physical Performance. Journal of the American College of Nutrition, 26(sup5), 542S-548S. https://pubmed.ncbi.nlm.nih.gov/17921463/

Nishiyasu, T. S., Shi, X. G., Mack, G. W., & Nadel, E. R. (1991). Effect of hypovolemia on forearm vascular resistance control during exercise in the heat. Journal of Applied Physiology, 71(4), 1382–1386. https://pubmed.ncbi.nlm.nih.gov/1757361/

Reyes, C., & Cornelis, M. (2018). Caffeine in the Diet: Country-Level Consumption and Guidelines. Nutrients, 10(11), 1772. https://pubmed.ncbi.nlm.nih.gov/30445721/

Ritz, P., & Berrut, G. (2005). The Importance of Good Hydration for Day-to-Day Health. Nutrition Reviews, 63, S6–S13. https://pubmed.ncbi.nlm.nih.gov/16028567/

Water: How much should you drink every day? (2020, October 14). Mayo Clinic. Retrieved April 14, 2022, from https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256?reDate=14042022

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Will McAuley is a London-based Personal Trainer and Nutrition Coach who’s writing has appeared in Men’s Fitness and GQ magazine, covering exercise, nutrition and health. He has a Master’s degree in Strength & Conditioning from Middlesex University in London, is a published scientific author in the Journal of Strength and Conditioning Research, and holds a Bachelor’s degree in Linguistics from Trinity College Dublin. 

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Facts About Water Completed

Facts about water.

Yes, of course the most obvious fact about water is that it is wet, at least in the liquid state. But, there are many more facts about water that make it a most fascinating substance, one that all life on and in the Earth depends on.

Earth's Water

Water Basics by Topic

Related Science Topics

• Water properties
• How Much Water is There on Earth?
• Where is Earth's Water?
• Water properties true/false quiz
• The water cycle
• Definitions of water terms

•   Water Science School HOME   •   Water Basics topics   •  Water Properties topics   •

Water numbers

Some of water's physical properties:

• Weight: 62.416 pounds/cubic foot at 32°F; 1,000 kilograms/cubic meter
• Weight: 61.998 pounds/cubic foot at 100°F; 993 kilograms/cubic meter
• Weight: 8.33 pounds/gallon; 1 kilogram/liter
• Density: 1 gram/cubic centimeter (cc) at 39.2°F, 0.95865 gram/cc at 212°F

Some water volume comparisons:

• 1 gallon = 4 quarts = 8 pints = 128 fluid ounces = 3.7854 liters
• 1 liter = 0.2642 gallons = 1.0568 quart
• 1 million gallons = 3.069 acre-feet = 133,685.64 cubic feet

Flow rates:

• 1 cubic foot/second (cfs) = 449 gallons/minute = 0.646 million gallons/day = 1.98 acre-feet/day

Water facts

Water is called the " universal solvent " because it dissolves more substances than any other liquid. This means that wherever water goes, either through the ground or through our bodies, it takes along valuable chemicals, minerals, and nutrients.

Pure water has a neutral pH of 7, which is neither acidic (less than 7) nor basic (greater than 7).

The water molecule is highly cohesive   — it is very sticky, meaning water molecules stick to each other. Water is the most cohesive among the non-metallic liquids.

Water molecules are also adhesive  in that they stick to other surfaces. Both cohesion and adhesion make water molecules very sticky!

Pure water, which you won't ever find in the natural environment, does not conduct electricity . Water becomes a conductor once it starts dissolving substances around it.

Water has a high heat index —it absorbs a lot of heat before it begins to get hot. This is why water is valuable to industries and in your car's radiator as a coolant. The high heat index of water also helps regulate the rate at which air changes temperature, which is why the temperature change between seasons is gradual rather than sudden, especially near the oceans.

Water has a very high surface tension . In other words, water is sticky and elastic, and tends to clump together in drops rather than spread out in a thin film, like rubbing alcohol. Surface tension is responsible for capillary action , which allows water (and its dissolved substances) to move through the roots of plants and through the tiny blood vessels in our bodies.

Air pressure affects the boiling point of water, which is why it takes longer to boil an egg at Denver, Colorado than at the beach. The higher the altitude, the lower the air pressure, the lower the boiling point of water, and thus, the longer time to hard-boil an egg. At sea level water boils at 212°F (100°C), while at 5,000 feet, water boils at 202.9°F (94.9 °C).

Other science topics related to water properties.

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The USGS Water Science School offers many resources to help teach students all about water. 

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Conductivity (electrical conductance) and water.

Specific Heat Capacity and Water

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Discharge from a Chinese fertilizer factory winds its way toward the Yellow River. Like many of the world's rivers, pollution remains an ongoing problem.

Water pollution is a rising global crisis. Here’s what you need to know.

The world's freshwater sources receive contaminants from a wide range of sectors, threatening human and wildlife health.

From big pieces of garbage to invisible chemicals, a wide range of pollutants ends up in our planet's lakes, rivers, streams, groundwater, and eventually the oceans. Water pollution—along with drought, inefficiency, and an exploding population—has contributed to a freshwater crisis , threatening the sources we rely on for drinking water and other critical needs.

Research has revealed that one pollutant in particular is more common in our tap water than anyone had previously thought: PFAS, short for poly and perfluoroalkyl substances. PFAS is used to make everyday items resistant to moisture, heat, and stains; some of these chemicals have such long half-lives that they are known as "the forever chemical."

Safeguarding water supplies is important because even though nearly 70 percent of the world is covered by water, only 2.5 percent of it is fresh. And just one percent of freshwater is easily accessible, with much of it trapped in remote glaciers and snowfields.

Water pollution causes

Water pollution can come from a variety of sources. Pollution can enter water directly, through both legal and illegal discharges from factories, for example, or imperfect water treatment plants. Spills and leaks from oil pipelines or hydraulic fracturing (fracking) operations can degrade water supplies. Wind, storms, and littering—especially of plastic waste —can also send debris into waterways.

Thanks largely to decades of regulation and legal action against big polluters, the main cause of U.S. water quality problems is now " nonpoint source pollution ," when pollutants are carried across or through the ground by rain or melted snow. Such runoff can contain fertilizers, pesticides, and herbicides from farms and homes; oil and toxic chemicals from roads and industry; sediment; bacteria from livestock; pet waste; and other pollutants .

Finally, drinking water pollution can happen via the pipes themselves if the water is not properly treated, as happened in the case of lead contamination in Flint, Michigan , and other towns. Another drinking water contaminant, arsenic , can come from naturally occurring deposits but also from industrial waste.

Freshwater pollution effects

Water pollution can result in human health problems, poisoned wildlife, and long-term ecosystem damage. When agricultural and industrial runoff floods waterways with excess nutrients such as nitrogen and phosphorus, these nutrients often fuel algae blooms that then create dead zones , or low-oxygen areas where fish and other aquatic life can no longer thrive.

Algae blooms can create health and economic effects for humans, causing rashes and other ailments, while eroding tourism revenue for popular lake destinations thanks to their unpleasant looks and odors. High levels of nitrates in water from nutrient pollution can also be particularly harmful to infants , interfering with their ability to deliver oxygen to tissues and potentially causing " blue baby syndrome ." The United Nations Food and Agriculture Organization estimates that 38 percent of the European Union's water bodies are under pressure from agricultural pollution.

Globally, unsanitary water supplies also exact a health toll in the form of disease. At least 2 billion people drink water from sources contaminated by feces, according to the World Health Organization , and that water may transmit dangerous diseases such as cholera and typhoid.

Freshwater pollution solutions

In many countries, regulations have restricted industry and agricultural operations from pouring pollutants into lakes, streams, and rivers, while treatment plants make our drinking water safe to consume. Researchers are working on a variety of other ways to prevent and clean up pollution. National Geographic grantee Africa Flores , for example, has created an artificial intelligence algorithm to better predict when algae blooms will happen. A number of scientists are looking at ways to reduce and cleanup plastic pollution .

There have been setbacks, however. Regulation of pollutants is subject to changing political winds, as has been the case in the United States with the loosening of environmental protections that prevented landowners from polluting the country’s waterways.

Anyone can help protect watersheds by disposing of motor oil, paints, and other toxic products properly , keeping them off pavement and out of the drain. Be careful about what you flush or pour down the sink, as it may find its way into the water. The U.S. Environmental Protection Agency recommends using phosphate-free detergents and washing your car at a commercial car wash, which is required to properly dispose of wastewater. Green roofs and rain gardens can be another way for people in built environments to help restore some of the natural filtering that forests and plants usually provide.

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Related topics.

• WATER POLLUTION
• ENVIRONMENT AND CONSERVATION
• FRESH WATER
• GROUNDWATER
• WATER QUALITY
• WATER RESOURCES

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The Origin of Earth’s Water

A new study supported in part by the NASA Astrobiology Institute is helping astrobiologists determine where Earth’s water came from. The team of researchers developed a new model for the origin of water on Earth that incorporates factors like water absorption on primordial dust grains, contributions from asteroid and planetary embryos, and water from comets. The model also accounts for the time of water delivery based on evidence from Earth’s geological record.

Liquid water is essential for life as we know it, and determining the origin of Earth’s water resources can help astrobiologists understand how life began on our planet. This information is also valuable in determining how habitable planets might form and evolve around distant stars. The paper was published in The Astrophysical Journal .

Liquid nitrogen fertilizer spill kills nearly 750,000 fish in Iowa river, officials say

The iowa department of natural resources recommends that individuals refrain from engaging in recreational activities on the east nishnabotna river and avoid collecting or consuming dead fish found in or around the river..

FILE – Waves of dead fish roll along Texas shore

Footage posted by Quintana Beach County Park shows dead fish being carried by the waves at Bryan Beach due to warming waters, according to local wildlife officials. (Video: Quintana Beach County Park via Storyful)

RED OAK, Iowa  – Hundreds of thousands of fish were killed earlier this month in a nearly 50-mile stretch of the East Nishnabotna River to the Missouri border due to a fertilizer spill in Iowa , state officials said.

On March 11, NEW Cooperative, Inc. in Red Oak reported to the Iowa Department of Natural Resources (DNR) that a spill occurred on their Montgomery County premises.

About 1,500 tons (equal to 265,000 gallons) of liquid nitrogen fertilizer (32% solution) was released into a drainage ditch, which subsequently entered the East Nishnabotna River. 

The spill happened due to an above-ground storage tank valve that was mistakenly left open over the weekend, the DNR said. 

DNR Fisheries staff said the fish kill affected the entire 49.8 miles of the East Nishnabotna and Nishnabotna Rivers downstream of the spill and extended to Missouri’s section of the Nishnabotna River before concluding near the junction with the Missouri River.

USDA AGAIN ASKS FOR HELP SQUASHING THESE INVASIVE BUGS

FILE – Thousands of dead menhaden fish are seen on the beach on December 19, 2005 in Wrightsville Beach, North Carolina.

(Logan Mock-Bunting / Getty Images)

As of Thursday, it was reported that a total of 749,242 fish had been killed, with the most affected species being the minnows, shiners, dace and chubs at 707,871.

Ongoing investigations are being conducted to determine the impact of the fertilizer release on other aquatic life.

According to Iowa state codes, a permit is required to discharge pollutants into a river. The DNR is collaborating with its legal department to determine the next course of action regarding enforcement and restitution for the loss of aquatic life. 

According to recent field tests, ammonia levels in the river are showing a decline. However, the DNR still recommends that individuals refrain from engaging in recreational activities on the river and avoid collecting or consuming dead fish found in or around the river.

All About the Ocean

The ocean covers 70 percent of Earth's surface.

Biology, Earth Science, Oceanography, Geography, Physical Geography

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This article is also available in Spanish .

The ocean covers 70 percent of Earth 's surface. It contains about 1.35 billion cubic kilometers (324 million cubic miles) of water, which is about 97 percent of all the water on Earth. The ocean makes all life on Earth possible, and makes the planet appear blue when viewed from space. Earth is the only planet in our solar system that is definitely known to contain liquid water. Although the ocean is one continuous body of water, oceanographers have divided it into five principal areas: the Pacific, Atlantic, Indian, Arctic, and Southern Oceans. The Atlantic, Indian, and Pacific Oceans merge into icy waters around Antarctica. Climate The ocean plays a vital role in climate and weather . The sun’s heat causes water to evaporate , adding moisture to the air. The oceans provide most of this evaporated water. The water vapor condenses to form clouds, which release their moisture as rain or other kinds of precipitation . All life on Earth depends on this process, called the water cycle . The atmosphere receives much of its heat from the ocean. As the sun warms the water, the ocean transfers heat to the atmosphere. In turn, the atmosphere distributes the heat around the globe. Because water absorbs and loses heat more slowly than land masses, the ocean helps balance global temperatures by absorbing heat in the summer and releasing it in the winter. Without the ocean to help regulate global temperatures, Earth’s climate would be bitterly cold. Ocean Formation After Earth began to form about 4.6 billion years ago, it gradually separated into layers of lighter and heavier rock. The lighter rock rose and formed Earth’s crust . The heavier rock sank and formed Earth’s core and mantle . The ocean’s water came from rocks inside the newly forming Earth. As the molten rocks cooled, they released water vapor and other gases. Eventually, the water vapor condensed and covered the crust with a primitive ocean. Today, hot gases from the Earth’s interior continue to produce new water at the bottom of the ocean. Ocean Floor Scientists began mapping the ocean floor in the 1920s. They used instruments called echo sounders , which measure water depths using sound waves . Echo sounders use sonar technology. Sonar is an acronym for SOund Navigation And Ranging. The sonar showed that the ocean floor has dramatic physical features, including huge mountains, deep canyons , steep cliffs , and wide plains . The ocean’s crust is a thin layer of volcanic rock called basalt . The ocean floor is divided into several different areas. The first is the continental shelf , the nearly flat, underwater extension of a continent. Continental shelves vary in width. They are usually wide along low-lying land, and narrow along mountainous coasts. A shelf is covered in sediment from the nearby continent. Some of the sediment is deposited by rivers and trapped by features such as natural dams. Most sediment comes from the last glacial period , or Ice Age, when the oceans receded and exposed the continental shelf. This sediment is called relict sediment . At the outer edge of the continental shelf, the land drops off sharply in what is called the continental slope . The slope descends almost to the bottom of the ocean. Then it tapers off into a gentler slope known as the continental rise. The continental rise descends to the deep ocean floor, which is called the abyssal plain . Abyssal plains are broad, flat areas that lie at depths of about 4,000 to 6,000 meters (13,123 to 19,680 feet). Abyssal plains cover 30 percent of the ocean floor and are the flattest feature on Earth. They are covered by fine-grained sediment like clay and silt. Pelagic sediments, the remains of small ocean organisms, also drift down from upper layers of the ocean. Scattered across abyssal plains are abyssal hills and underwater volcanic peaks called seamounts. Rising from the abyssal plains in each major ocean is a huge chain of mostly undersea mountains. Called the mid-ocean ridge , the chain circles Earth, stretching more than 64,000 kilometers (40,000 miles). Much of the mid-ocean ridge is split by a deep central rift, or crack. Mid-ocean ridges mark the boundaries between tectonic plates . Molten rock from Earth’s interior wells up from the rift, building new seafloor in a process called seafloor spreading . A major portion of the ridge runs down the middle of the Atlantic Ocean and is known as the Mid-Atlantic Ridge. It was not directly seen or explored until 1973. Some areas of the ocean floor have deep, narrow depressions called ocean trenches . They are the deepest parts of the ocean. The deepest spot of all is the Challenger Deep , which lies in the Mariana Trench in the Pacific Ocean near the island of Guam. Its true depth is not known, but the most accurate measurements put the Challenger Deep at 11,000 meters (36,198 feet) below the ocean’s surface—that’s more than 2,000 meters (6,000 feet) taller than Mount Everest, Earth’s highest point. The pressure in the Challenger Deep is about eight tons per square inch.

Ocean Life Zones From the shoreline to the deepest seafloor, the ocean teems with life. The hundreds of thousands of marine species range from microscopic algae to the largest creature to have ever lived on Earth, the blue whale. The ocean has five major life zones, each with organisms uniquely adapted to their specific marine ecosystem . The epipelagic zone (1) is the sunlit upper layer of the ocean. It reaches from the surface to about 200 meters (660 feet) deep. The epipelagic zone is also known as the photic or euphotic zone, and can exist in lakes as well as the ocean. The sunlight in the epipelagic zone allows photosynthesis to occur. Photosynthesis is the process by which some organisms convert sunlight and carbon dioxide into energy and oxygen . In the ocean, photosynthesis takes place in plants and algae. Plants such as seagrass are similar to land plants—they have roots, stems, and leaves. Algae is a type of aquatic organism that can photosynthesize sunlight. Large algae such as kelp are called seaweed . Phytoplankton also live in the epipelagic zone. Phytoplankton are microscopic organisms that include plants, algae, and bacteria. They are only visible when billions of them form algal blooms , and appear as green or blue splotches in the ocean. Phytoplankton are a basis of the ocean food web . Through photosynthesis, phytoplankton are responsible for almost half the oxygen released into Earth’s atmosphere. Animals such as krill (a type of shrimp), fish, and microscopic organisms called zooplankton all eat phytoplankton. In turn, these animals are eaten by whales, bigger fish, ocean birds, and human beings. The next zone down, stretching to about 1,000 meters (3,300 feet) deep, is the mesopelagic zone (2). This zone is also known as the twilight zone because the light there is very dim. The lack of sunlight means there are no plants in the mesopelagic zone, but large fish and whales dive there to hunt prey . Fish in this zone are small and luminous . One of the most common is the lanternfish, which has organs along its side that produce light. Sometimes, animals from the mesopelagic zone (such as sperm whales ( Physeter macrocephalus ) and squid) dive into the bathypelagic zone (3), which reaches to about 4,000 meters (13,100 feet) deep. The bathypelagic zone is also known as the midnight zone because no light reaches it. Animals that live in the bathypelagic zone are small, but they often have huge mouths, sharp teeth, and expandable stomachs that let them eat any food that comes along. Most of this food comes from the remains of plants and animals drifting down from upper pelagic zones. Many bathypelagic animals do not have eyes because they are unneeded in the dark. Because the pressure is so great and it is so difficult to find nutrients , fish in the bathypelagic zone move slowly and have strong gills to extract oxygen from the water. The water at the bottom of the ocean, the abyssopelagic zone (4), is very salty and cold (2 degrees Celsius, or 35 degrees Fahrenheit). At depths up to 6,000 meters (19,700 feet), the pressure is very strong—11,000 pounds per square inch. This makes it impossible for most animals to live. Animals in this zone have bizarre adaptations to cope with their ecosystem. Many fish have jaws that look unhinged. The jaws allow them to drag their open mouth along the seafloor to find food, such as mussels, shrimp, and microscopic organisms. Many of the animals in this zone, including squid and fish, are bioluminescent. Bioluminescent organisms produce light through chemical reactions in their bodies. A type of angler fish, for example, has a glowing growth extending in front of its huge, toothy mouth. When smaller fish are attracted to the light, the angler fish simply snaps its jaws to eat its prey. The deepest ocean zone, found in trenches and canyons, is called the hadalpelagic zone (5). Few organisms live here. They include tiny isopods , a type of crustacean related to crabs and shrimp. Invertebrates such as sponges and sea cucumbers thrive in the abyssopelagic and hadalpelagic zones. Like many sea stars and jellyfish, these animals are almost entirely dependent on falling parts of dead or decaying plants and animals, called marine detritus . Not all bottom dwellers, however, depend on marine detritus. In 1977, oceanographers discovered a community of creatures on the ocean floor that feed on bacteria around openings called hydrothermal vents. These vents discharge superheated water enriched with minerals from Earth’s interior. The minerals nourish unique bacteria, which in turn nourish creatures such as crabs, clams, and tube worms. Ocean Currents Currents are streams of water running through a larger body of water. Oceans, rivers, and streams have currents. The ocean’s salinity and temperature and the coast’s geographic features determine an ocean current’s behavior. Earth’s rotation and wind also influence ocean currents. Currents flowing near the surface transport heat from the tropics to the poles and move cooler water back toward the Equator . This keeps the ocean from becoming extremely hot or cold. Deep, cold currents transport oxygen to organisms throughout the ocean. They also carry rich supplies of nutrients that all living things need. The nutrients come from plankton and the remains of other organisms that drift down and decay on the ocean floor. Along some coasts, winds and currents produce a phenomenon called upwelling . As winds push surface water away from shore, deep currents of cold water rise to take its place. This upwelling of deep water brings up nutrients that nourish new growth of plankton, providing food for fish. Ocean food chains constantly recycle food and energy this way.

Some ocean currents are enormous and extremely powerful. One of the most powerful is the Gulf Stream , a warm surface current that originates in the tropical Caribbean Sea and flows northeast along the eastern coast of the United States. The Gulf Stream measures up to 80 kilometers (50 miles) wide and is more than a kilometer (3,281 feet) deep. Like other ocean currents, the Gulf Stream plays a major role in climate. As the current travels north, it transfers moisture from its warm tropical waters to the air above. Westerly, or prevailing, winds carry the warm, moist air to the British Isles and to Scandinavia , causing them to have milder winters than they otherwise would experience at their northern latitudes . Northern parts of Norway are near the Arctic Circle but remain ice-free for most of the year because of the Gulf Stream. The weather pattern known as El Niño includes a change to the Humboldt Current (also called the Peru Current) off the western coast of South America. In El Niño conditions, a current of warm surface water travels east along the Equator and prevents the normal upwelling of the cold, nutrient-rich Humboldt Current. El Niño, which can devastate the fisheries of Peru and Ecuador, occurs every two to seven years, usually in December. The paths of ocean currents are partially determined by Earth’s rotation. This is known as the Coriolis effect . It causes large systems, such as winds and ocean currents that would normally move in a straight line, to veer to the right in the northern hemisphere and to the left in the southern hemisphere . People and the Ocean For thousands of years, people have depended on the ocean as a source of food and as a route for trade and exploration . Today, people continue to travel on the ocean and rely on the resources it contains. Nations continue to negotiate how to determine the extent of their territory beyond the coast. The United Nations’ Law of the Sea treaty established exclusive economic zones (EEZs), extending 200 nautical miles (230 miles) beyond a nation’s coastline. Even though some countries have not signed or ratified the treaty (including the U.S.), it is regarded as standard. Russia has proposed extending its EEZ beyond 200 nautical miles because two mid-ocean ridges, the Lomonosov and Medeleev Ridges, are extensions of the continental shelf belonging to Russia. This territory includes the North Pole. Russian explorers in a submersible vehicle planted a metal Russian flag on the disputed territory in 2007. Through the centuries, people have sailed the ocean on trade routes . Today, ships still carry most of the world’s freight , particularly bulky goods such as machinery, grain, and oil . Ocean ports are areas of commerce and culture. Water and land transportation meet there, and so do people of different professions: businesspeople who import and export goods and services; dockworkers who load and unload cargo ; and ships’ crews. Ports also have a high concentration of migrants and immigrants with a wide variety of ethnicities, nationalities, languages, and religions. Important ports in the U.S. are New York/ New Jersey and New Orleans. The busiest ports around the world include the Port of Shanghai in China and the Port of Rotterdam in the Netherlands. Ocean ports are also important for a nation’s armed forces. Some ports are used exclusively for military purposes, although most share space with commercial businesses. “The sun never sets on the British Empire” is a phrase used to explain the scope of the empire of Great Britain , mostly in the 19th century. Although based on the small European island nation of Great Britain, British military sea power extended its empire from Africa to the Americas, Asia, and Australia. Scientists and other experts hope the ocean will be used more widely as a source of renewable energy . Some countries have already harnessed the energy of ocean waves, temperature, currents, or tides to power turbines and generate electricity. One source of renewable energy are generators that are powered by tidal streams or ocean currents. They convert the movement of currents into energy. Ocean current generators have not been developed on a large scale, but are working in some places in Ireland and Norway. Some conservationists criticize the impact the large constructions have on the marine environment. Another source of renewable energy is ocean thermal energy conversion (OTEC). It uses the difference in temperature between the warm, surface water and cold, deep water to run an engine. OTEC facilities exist in places with significant differences in ocean depth: Japan, India and the U.S. state of Hawai'i, for instance. An emerging source of renewable energy is salinity gradient power , also known as osmotic power. It is an energy source that uses the power of freshwater entering into saltwater. This technology is still being developed, but it has potential in delta areas where fresh river water is constantly interacting with the ocean. Fishing Fishers catch more than 90 million tons of seafood each year, including more than 100 species of fish and shellfish . Millions of people, from professional fishers to business owners like restaurant owners and boat builders, depend on fisheries for their livelihood . Fishing can be classified in two ways. In subsistence fishing, fishers use their catch to help meet the nutritional needs of their families or communities. In commercial fishing , fishers sell their catch for money, goods or services. Popular subsistence and commercial fish are tuna, cod, and shrimp. Ocean fishing is also a popular recreational sport. Sport fishing can be competitive or noncompetitive. In sport fishing tournaments, individuals or teams compete for prizes based on the size of a particular species caught in a specific time period. Both competitive and noncompetitive sport fishers need licenses to fish, and may or may not keep the caught fish. Increasingly, sport fishers practice catch-and-release fishing, where a fish is caught, measured, weighed, and often recorded on film before being released back to the ocean. Popular game fish (fish caught for sport) are tuna and marlin. Whaling is a type of fishing that involves the harvesting of whales and dolphins. It has declined in popularity since the 19th century but is still a way of life for many cultures, such as those in Scandinavia, Japan, Canada, and the Caribbean. The ocean offers a wealth of fishing and whaling resources, but these resources are threatened. People have harvested so much fish and marine life for food and other products that some species have disappeared. During the 1800s and early 1900s, whalers killed thousands of whales for whale oil (wax made from boiled blubber ) and ivory (whales’ teeth). Some species, including the blue whale ( Balaenoptera musculus ) and the right whale, were hunted nearly to extinction . Many species are still endangered today. In the 1960s and 1970s, catches of important food fish, such as herring in the North Sea and anchovies in the Pacific, began to drop off dramatically. Governments took notice of overfishing —harvesting more fish than the ecosystem can replenish . Fishers were forced to go farther out to sea to find fish, putting them at risk. (Deep-sea fishing is one of the most dangerous jobs in the world.) Now, they use advanced equipment, such as electronic fish finders and large gill nets or trawling nets, to catch more fish. This means there are far fewer fish to reproduce and replenish the supply. In 1992, the collapse, or disappearance, of cod in Canada’s Newfoundland Grand Banks put 40,000 fishers out of work. A ban was placed on cod fishing, and to this day, neither the cod nor the fisheries have recovered. To catch the dwindling numbers of fish, most fishers use trawl nets. They drag the nets along the seabed and across acres of ocean. These nets accidentally catch many small, young fish and mammals. Animals caught in fishing nets meant for other species are called bycatch . The fishing industry and fisheries management agencies argue about how to address the problem of bycatch and overfishing. Those involved in the fishing industry do not want to lose their jobs, while conservationists want to maintain healthy levels of fish in the ocean. A number of consumers are choosing to purchase sustainable seafood . Sustainable seafood is harvested from sources (either wild or farmed) that do not deplete the natural ecosystem. Mining and Drilling Many minerals come from the ocean. Sea salt is a mineral that has been used as a flavoring and preservative since ancient times. Sea salt has many additional minerals, such as calcium, that ordinary table salt lacks. Hydrothermal vents often form seafloor massive sulfide (SMS) deposits , which contain precious metals. These SMS deposits sit on the ocean floor, sometimes in the deep ocean and sometimes closer to the surface. New techniques are being developed to mine the seafloor for valuable minerals such as copper, lead, nickel, gold, and silver. Mining companies employ thousands of people and provide goods and services for millions more. Critics of undersea mining maintain that it disrupts the local ecology . Organisms—corals, shrimp, mussels—that live on the seabed have their habitat disturbed, upsetting the food chain. In addition, destruction of habitat threatens the viability of species that have a narrow niche . Maui’s dolphin ( Cephalorhynchus hectori maui ), for instance, is a critically endangered species native to the waters of New Zealand’s North Island. The numbers of Maui’s dolphin are already reduced because of bycatch. Seabed mining threatens its habitat, putting it at further risk of extinction. Oil is one of the most valuable resources taken from the ocean today. Offshore oil rigs pump petroleum from wells drilled into the continental shelf. About one-quarter of all oil and natural gas supplies now comes from offshore oil deposits around the world. Offshore drilling requires complex engineering . An oil platform can be constructed directly onto the ocean floor, or it can “float” above an anchor. Depending on how far out on the continental shelf an oil platform is located, workers may have to be flown in. Underwater, or subsea, facilities are complicated groups of drilling equipment connected to each other and a single oil rig. Subsea production often requires remotely operated underwater vehicles (ROVs). Some countries invest in offshore drilling for profit and to prevent reliance on oil from other regions. The Gulf of Mexico near the U.S. states of Texas and Louisiana is heavily drilled. Several European countries, including the United Kingdom, Denmark, and the Netherlands, drill in the North Sea. Offshore drilling is a complicated and expensive program, however. There are a limited number of companies that have the knowledge and resources to work with local governments to set up offshore oil rigs. Most of these companies are based in Europe and North America, although they do business all over the world. Some governments have banned offshore oil drilling. They cite safety and environmental concerns. There have been several accidents where the platform itself has exploded, at the cost of many lives. Offshore drilling also poses threats to the ocean ecosystem. Spills and leaks from oil rigs and oil tankers that transport the material seriously harm marine mammals and birds. Oil coats feathers, impairing birds’ ability to maintain their body temperature and remain buoyant in the water. The fur of otters and seals are also coated, and oil entering the digestive tract of animals may damage their organs. Offshore oil rigs also release metal cuttings, minute amounts of oil, and drilling fluid into the ocean every day. Drilling fluid is the liquid used with machinery to drill holes deep in the planet. This liquid can contain pollutants such as toxic chemicals and heavy metals . Pollution Most oil pollution does not come from oil spills, however. It comes from the runoff of pollutants into streams and rivers that flow into the ocean. Most runoff comes from individual consumers. Cars, buses, motorcycles, and even lawn mowers spill oil and grease on roads, streets, and highways. (Runoff is what makes busy roads shiny and sometimes slippery.) Storm drains or creeks wash the runoff into local waterways, which eventually flow into the ocean. The largest U.S. oil spill in the ocean took place in Alaska in 1989, by the tanker Exxon Valdez . The Exxon Valdez spilled at least 10 million gallons of oil into Prince William Sound. In comparison, American and Canadian consumers spill about 16 million gallons of oil runoff into the Atlantic and Pacific Oceans every year. For centuries, people have used the ocean as a dumping ground for sewage and other wastes. In the 21st century, the wastes include not only oil, but also chemical runoff from factories and agriculture . These chemicals include nitrates and phosphates , which are often used as fertilizers . These chemicals encourage algae blooms. An algae bloom is an increase in algae and bacteria that threatens plants and other marine life. Algae blooms limit the amount of oxygen in a marine environment, leading to what are known as dead zones , where little life exists beneath the ocean’s surface. Algae blooms can spread across hundreds or even thousands of miles. Another source of pollution is plastics . Most ocean debris, or garbage, is plastic thrown out by consumers. Plastics such as water bottles, bags, six-pack rings, and packing material put marine life at risk. Sea animals are harmed by the plastic either by getting tangled in it or by eating it. An example of marine pollution consisting mainly of plastics is the Great Pacific Garbage Patch . The Great Pacific Garbage Patch is a floating dump in the North Pacific. It’s about twice the size of Texas and probably contains about 100 million tons of debris. Most of this debris comes from the western coast of North America (the U.S. and Canada) and the eastern coast of Asia (Japan, China, Russia, North Korea, and South Korea). Because of ocean currents and weather patterns, the patch is a relatively stable formation and contains new and disintegrating debris. The smaller pieces of plastic debris are eaten by jellyfish or other organisms, and are then consumed by larger predators in the food web. These plastic chemicals may then enter a human’s diet through fish or shellfish. Another source of pollution is carbon dioxide. The ocean absorbs most carbon dioxide from the atmosphere. Carbon dioxide, which is necessary for life, is known as a greenhouse gas and traps radiation in Earth’s atmosphere. Carbon dioxide forms many acids, called carbonic acids , in the ocean. Ocean ecosystems have adapted to the presence of certain levels of carbonic acids, but the increase in carbon dioxide has led to an increase in ocean acids. This ocean acidification erodes the shells of animals such as clams, crabs, and corals. Global Warming Global warming contributes to rising ocean temperatures and sea levels . Warmer oceans radically alter the ecosystem. Global warming causes cold-water habitats to shrink, meaning there is less room for animals such as penguins, seals, or whales. Plankton, the base of the ocean food chain, thrives in cold water. Warming water means there will be less plankton available for marine life to eat. Melting glaciers and ice sheets contribute to sea level rise . Rising sea levels threaten coastal ecosystems and property. River deltas and estuaries are put at risk for flooding. Coasts are more likely to suffer erosion . Seawater more often contaminates sources of fresh water. All these consequences—flooding, erosion, water contamination—put low-lying island nations, such as the Maldives in the Indian Ocean, at high risk for disaster. To find ways to protect the ocean from pollution and the effects of climate change, scientists from all over the world are cooperating in studies of ocean waters and marine life. They are also working together to control pollution and limit global warming. Many countries are working to reach agreements on how to manage and harvest ocean resources. Although the ocean is vast, it is more easily polluted and damaged than people once thought. It requires care and protection as well as expert management. Only then can it continue to provide the many resources that living things—including people—need.

The Most Coast . . . Canada has 202,080 kilometers (125,567 miles) of coastline. Short But Sweet . . . Monaco has four kilometers (2.5 miles) of coastline.

No, the Toilet Doesn't Flush Backward in Australia The Coriolis effect, which can be seen in large-scale phenomena like trade winds and ocean currents, cannot be duplicated in small basins like sinks.

Extraterrestrial Oceans Mars probably had oceans billions of years ago, but ice and dry seabeds are all that remain today. Europa, one of Jupiter's moons, is probably covered by an ocean of water more than 96 kilometers (60 miles) deep, but it is trapped beneath a layer of ice, which the warmer water below frequently cracks. One of Saturn's moons, Enceladus, has cryovolcanism, or ice volcanoes. Instead of erupting with lava, ice volcanoes erupt with water, ammonia, or methane. Ice volcanoes may indicate oceanic activity.

International Oil Spill The largest oil spill in history, the Gulf War oil spill, released at least 40 million gallons of oil into the Persian Gulf. Valves at the Sea Island oil terminal in Kuwait were opened on purpose after Iraq invaded Kuwait in 1991. The oil was intended to stop a landing by U.S. Marines, but the oil drifted south to the shores of Saudi Arabia. A study of the Gulf War oil spill (conducted by the United Nations, several countries in the Middle East and the United States) found that most of the spilled oil evaporated and caused little damage to the environment.

Ocean Seas The floors of the Caspian Sea and the Black Sea are more like the ocean than other seas they do not rest on a continent, but directly on the ocean's basalt crust.

Early Ocean Explorers Polynesian people navigated a region of the Pacific Ocean now known as the Polynesian Triangle by 700 C.E. The corners of the Polynesian Triangle are islands: the American state of Hawai'i, the country of New Zealand, and the Chilean territory of Easter Island (also known as Rapa Nui). The distance between Easter Island and New Zealand, the longest length of the Polynesian Triangle, is one-quarter of Earth's circumference, more than 10,000 kilometers (6,200 miles). Polynesians successfully traveled these distances in canoes. It would be hundreds of years before another culture explored the ocean to this extent.

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Related Resources

A Solar Eclipse Means Big Science

By Katrina Miller April 1, 2024

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On April 8, cameras all over North America will make a “megamovie” of the sun’s corona, like this one from the 2017 eclipse. The time lapse will help scientists track the behavior of jets and plumes on the sun’s surface.

There’s more science happening along the path of totality →

An app named SunSketcher will help the public take pictures of the eclipse with their phones.

Scientists will use these images to study deviations in the shape of the solar surface , which will help them understand the sun’s churning behavior below.

The sun right now is approaching peak activity. More than 40 telescope stations along the eclipse’s path will record totality.

By comparing these videos to what was captured in 2017 — when the sun was at a lull — researchers can learn how the sun’s magnetism drives the solar wind, or particles that stream through the solar system.

Students will launch giant balloons equipped with cameras and sensors along the eclipse’s path.

Their measurements may improve weather forecasting , and also produce a bird’s eye view of the moon’s shadow moving across the Earth.

Ham radio operators will send signals to each other across the path of totality to study how the density of electrons in Earth’s upper atmosphere changes .

This can help quantify how space weather produced by the sun disrupts radar communication systems.

(Animation by Dr. Joseph Huba, Syntek Technologies; HamSCI Project, Dr. Nathaniel Frissell, the University of Scranton, NSF and NASA.)

NASA is also studying Earth’s atmosphere, but far from the path of totality.

In Virginia, the agency will launch rockets during the eclipse to measure how local drops in sunlight cause ripple effects hundreds of miles away . The data will clarify how eclipses and other solar events affect satellite communications, including GPS.

Biologists in San Antonio plan to stash recording devices in beehives to study how bees orient themselves using sunlight , and how the insects respond to the sudden atmospheric changes during a total eclipse.

Two researchers in southern Illinois will analyze social media posts to understand tourism patterns in remote towns , including when visitors arrive, where they come from and what they do during their visits.

Results can help bolster infrastructure to support large events in rural areas.

Read more about the eclipse:

Our Coverage of the Total Solar Eclipse

Hearing the Eclipse:  A device called LightSound is being distributed to help the blind and visually impaired experience what they can’t see .

Maine Brac es Itself :  Businesses and planning committees are eager for visitors, but some in remote Aroostook County are not sure how they feel  about lying smack in the path of totality.

A Dark Day for Buffalo:  When the sky above Buffalo briefly goes dark  on the afternoon of April 8, the city will transcend its dreary place in the public consciousness — measured as it so often is by snowstorms — if only for about three minutes. The city can’t wait.

Under the Moon’s Shadow:  The late Jay Pasachoff, who spent a lifetime chasing eclipses , inspired generations of students to become astronomers by dragging them to the ends of the Earth for a few precarious moments of ecstasy.

A Rare Return:  It is rare for a total solar eclipse to hit the same place twice — once every 366 years on average. People in certain areas will encounter April 8’s eclipse  about seven years after they were near the middle of the path of the “Great American Eclipse.”

A Small City’s Big Plans:  Let the big cities have their eclipse mega-events. In Plattsburgh, N.Y., success looks different  for everyone stopping to look up.

 No Power Outages:  When the sky darkens during the eclipse, electricity production in some parts of the country will drop so sharply that it could theoretically leave tens of millions of homes in the dark. In practice, hardly anyone will notice  a sudden loss of energy.

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